Edward Hodgson

Modeling Space Suit Mobility: Applications to Design and Operations

Computer simulation of extravehicular activity (EVA) is increasingly being used in planning and training for EVA. A space suit model is an important, but often overlooked, component of an EVA simulation. Because of the inherent difficulties in collecting angle and torque data for space suit joints in realistic conditions, little data exists on the torques that a space suit’s wearer must provide in order to move in the space suit. A joint angle and torque database was compiled on the Extravehicular Maneuvering Unit (EMU), with a novel measurement technique that used both human test subjects and an instrumented robot. Using data collected in the experiment, a hysteresis modeling technique was used to predict EMU joint torques from joint angular positions. The hysteresis model was then applied to EVA operations by mapping out the reach and work envelopes for the EMU.

Phase Change Material Trade Study: A Comparison Between Wax and Water for Manned Spacecraft

Phase change material heat sinks have been recognized as an important tool in optimizing thermal control systems for space exploration vehicles and habitats that must deal with widely varying thermal loads and environments. In order to better focus technology investment in this arena, NASA has supported a trade study with the objective of identifying where the best potential pay-off can be found among identified aqueous and paraffin wax phase change materials and phase change material heat sink design approaches. The study used a representative exploration mission with well understood parameters to support the trade. Additional sensitivity studies were performed to ensure the applicability of study results across varying systems and destinations. Results from the study indicate that a water ice PCM heat sink has the potential to decrease the equivalent system mass of the mission s vehicle through a combination of a smaller heat sink and a slight 5% increase in radiator size or the addition of a lightweight heat pump. An evaluation of existing and emerging PCM heat sink technologies indicates that further significant mass savings should be achievable through continued development of those technologies. The largest mass savings may be realized by managing the location of the liquid and the solid in the heat sink to eliminate the melting and freezing pressure of wax and water, respectively, while also accommodating the high structural loads expected on future manned launch vehicles.

Investigation of EVA Information Interface Technology in a Mars Analog Arctic Field Science Setting

Hamilton Sundstrand Space Systems International (HSSSI) participated with the National Aeronautics and Space Administration (NASA), the Search for Extraterrestrial Intelligence (SETI) Institute and Simon Fraser University in the 2001 field season of NASA’s Haughton-Mars Project (HMP) to study information technologies concepts and hardware systems for advanced Extravehicular Activity (EVA). The research was focused on developing an improved understanding of the uses of the interface in an exploration / field science context. Interface integration with communication, navigation and scientific data systems, and the special challenges posed by the expeditionary environment were investigated. This paper presents a discussion of the field test systems, test activities and results. Recommendations for future, higher fidelity research are included.

Preliminary Testing of a Pressurized Space Suit and Candidate Fabrics Under Simulated Mars Dust Storm and Dust Devil Conditions

In August 2009 YAP Films (Toronto) received permission from all entities involved to create a documentary film illustrating what it might be like to be on the surface of Mars in a space suit during a dust storm or in a dust devil. The science consultants on this project utilized this opportunity to collect data which could be helpful to assess the durability of current space suit construction to the Martian environment. The NDX-1 prototype planetary space suit developed at the University of North Dakota was used in this study. The suit features a hard upper torso garment, and a soft lower torso and boots assembly. On top of that, a nylon-cotton outer layer is used to protect the suit from dust. Unmanned tests were carried out in the Martian Surface Wind Tunnel (MARSWIT) at the NASA Ames Research Center, with the suit pressurized to 10 kPa gauge. These tests blasted the space suit upper torso and helmet, and a collection of nine candidate outer layer fabrics, with wind-borne simulant for five different 10 min tests under both terrestrial and Martian surface pressures. The infiltration of the dust through the outer fabric of the space suit was photographically documented. The nine fabric samples were analyzed under light and electron microscopes for abrasion damage. Manned tests were carried out at Showbiz Studios (Van Nuys, California) with the pressure maintained at 20 2 kPa gauge. A large fan-created vortex lifted Martian dust simulant (Fullers Earth or JSC Mars-1) off of the floor, and one of the authors (Lee) wearing the NDX-1 space suit walked through it to judge both subjectively and objectively how the suit performed under these conditions. Both the procedures to scale the tests to Martian conditions and the results of the infiltration and abrasion studies will be discussed.

Development of a Prototype Water Pump for Future Space Suit Applications

NASA s next generation of space suit systems will place new demands on the pump used to circulate cooling water through the life support system and the crew s liquid cooling garment. Long duration missions and frequent EVA require increased durability and reliability; limited resupply mass requirements demand compatibility with recycled water, and changing system design concepts demand increased tolerance for dissolved and free gas and the ability to operate over a broader range of flow rates and discharge pressure conditions. This paper describes the development of a positive displacement prototype pump to meet these needs. A gerotor based design has been adapted to meet pump performance, gas tolerance, and durability requirements while providing a small, lightweight pump assembly. This design has been detailed and implemented using materials selected to address anticipated water quality and mission needs as a prototype unit for testing in NASA laboratories. Design requirements, pump technology selection and design, performance testing and test results will be discussed.

Evolutionary Development of Exploration EVA Systems Design and Operations Through Analog Field Tests: Lessons from the NASA Haughton-Mars Project, 2008-2010

Hamilton Sundstrand has collaborated with NASA’s Haughton-Mars Project (HMP) over the past decade in order to develop a better understanding of the design requirements for, and challenges facing, Extravehicular Activity (EVA) systems for planetary exploration. Each summer, mock-up systems emphasizing specific aspects of EVA system design have been deployed to the Haughton Crater test site on Devon Island, High Arctic, for evaluation in the context of NASA’s broader analog environment research effort. During the summers of 2008, 2009, and 2010, the systems deployed and field evaluation activities have focused on the effective integration of a rear entry EVA suit system design and suit-port interface with evolving NASA exploration system concepts. The fielded mock-up systems, although of limited fidelity and technical maturity, have contributed significantly to NASA’s investigation of exploration operational concepts, and the field test experience has contributed directly to advances in design concepts for EVA suit system – suit-port integration. This paper describes the field research activities in which HS participated, HS mock-up systems employed, and principal test results at HMP over the past three years. It discusses lessons learned and resulting design concept improvements, and illustrates the role of analog environment field research experience in exploration system development and of the potential synergy between evolving hardware designs and operational concepts in analog environment field tests.

Prototype Cryogenic Oxygen Storage and Delivery Subsystem for Advanced Spacesuits

Future spacesuit systems for the exploration of Mars will need to be much lighter than current designs while at the same time reducing the consumption of water for crew cooling. One of the technology paths NASA has identified to achieve these objectives is the replacement of current high pressure oxygen storage technology in EVA systems with cryogenic technology that can simultaneously reduce the mass of tankage required for oxygen storage and enable the use of the stored oxygen as a means of cooling the EVA astronaut. During the past year NASA has funded Hamilton Sundstrand production of a prototype system demonstrating this capability in a design that will allow the cryogenic oxygen to be used in any attitude and gravity environment. This paper will describe the design and manufacture of the prototype system and present the results of preliminary testing to verify its performance characteristics. The potential significance and application of the system will also be discussed.

Is there space for wearables

The integration of man, a protective suit, and computer has been an integral part of the vision presented in science fiction movies and books since long before the Borg strode across the Star Trek screen. It is easy to envision using computers in countless ways to augment human perception, recall, and reactions to provide huge gains in personal safety and capability. However, the reality for todays space walker falls well short of these visionary projections. Once the confines of the Space Shuttle or Space Station is left behind, computer support is pretty much limited by the throughput of a simple one line text display and the bandwidth of a human voice relay channel. Practical issues of device size and power consumption, environmental tolerance, and display and control interface compatibility with the real design constraints of space suits have frustrated multiple attempts over the past 20 years to make the envisioned possibilities real. NASA and industry efforts to produce advanced EVA computer task support systems using heads up displays, wrist mounted displays, and modifications of the current chest mounted display and control system have fallen short in the demanding environment of NASAs space missions. So far, the correct balance of utility, reliability, compact size, and weight, has eluded developers and space has remained the unconquered frontier for wearables. Undaunted, the faithful have continued the quest, and with the dramatic advances in hardware and software systems we have seen over the past decade, the path to achieving the vision seems, at last, to be clearing. Key elements in this development are the emergence of display technologies that make it practical to rapidly present large amounts of information to a suited crew person in space, advances in processing capability and speech recognition software that offer the potential for a flexible EVA control interface, and the combination of high density storage and wireless network technologies multiplying the amounts and kinds of information upon which the EVA astronaut can draw. Together with emerging visions of exploration missions that will demand complex interactions and unprecedented real time support, these developments lead to the conclusion that there will, and must be, space for wearables and wearables for space.

Maturing Pump Technology for Extravehicular Activity Applications in a Collaborative Environment

The transition from low Earth orbit extravehicular activity (EVA) for construction and maintenance activities to planetary surface EVA on asteroids, moons, and, ultimately, Mars demands a new spacesuit system. NASA’s development of that system has resulted in dramatically different pumping requirements from those in the current spacesuit system. Hamilton Sundstrand, Cascon, and NASA are collaborating to develop and mature a pump that will reliably meet those new requirements in space environments and within the design constraints imposed by spacesuit system integration. That collaboration, which began in the NASA purchase of a pump prototype for test evaluation, is now entering a new phase of development. A second-generation pump reflecting the lessons learned in NASA’s testing of the original prototype will be developed under Hamilton Sundstrand internal research funding and ultimately tested in an integrated Advanced Portable Life Support System in NASA laboratories at Johnson Space Center. This partnership is providing benefit to both industry and NASA by supplying a custom component for EVA integrated testing at no cost to the government while providing test data for industry that would otherwise be difficult or impossible to duplicate in industry laboratories. This paper discusses the evolving collaborative process, component requirements, and design development based on early NASA test experience, component stand-alone test results, and near-term plans for integrated testing at Johnson Space Center.